Imaging lens and imaging apparatus equipped with the imaging lens

ABSTRACT

An imaging lens is constituted by six lenses, including, in order from the object side to the image side: a positive first lens having a convex surface toward the object side; a negative second lens; a positive third lens, which is a meniscus lens having a convex surface toward the object side; a positive fourth lens; a negative fifth lens having a concave surface toward the object side; and a negative sixth lens, of which the image toward the image side is of an aspherical shape which is concave in the vicinity of the optical axis and convex at the peripheral portion thereof. Conditional formulae related to the focal length f of the entire lens system, the focal length f 1  of the first lens, and the focal length f 4  of the fourth lens is satisfied. 
       1.54&lt; f/f 4&lt;3 
       0.5&lt; f/f 1&lt;1

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of PCT InternationalApplication No. PCT/JP2013/007641 filed on Dec. 26, 2013, which claimspriority under 35 U.S.C. §119(a) to Japanese Patent Application No.2013-063612 filed on Mar. 26, 2013. Each of the above applications ishereby expressly incorporated by reference in its entirety, into thepresent application.

BACKGROUND

The present disclosure is related to a fixed focus imaging lens forforming optical images of subjects onto an imaging element such as a CCD(Charge Coupled Device) and a CMOS (Complementary Metal OxideSemiconductor). The present disclosure is also related to an imagingapparatus provided with the imaging lens that performs photography suchas a digital still camera, a cellular telephone with a built in camera,a PDA (Personal Digital Assistant), a smart phone, a tablet typeterminal, and a portable gaming device.

Accompanying the recent spread of personal computers in households,digital still cameras capable of inputting image data such asphotographed scenes and portraits into personal computers are rapidlybecoming available. In addition, many cellular telephones, smart phones,and tablet type terminals are being equipped with camera modules forinputting images. Imaging elements such as CCD's and CMOS's are employedin these devices having photography functions. Recently, the resolutionsof these imaging elements are increasing, and there is demand forincreased resolution and increased performance in imaging lenses. Thistrend is particularly significant in smart phones. In recent years, sixlens configurations are becoming the mainstream in imaging lenses whichare mounted in smart phones. The imaging lens disclosed in Korean PatentPublication No. 2010-0040357 below has been proposed as an imaging lenshaving a six lens configuration in the above field.

SUMMARY

Miniaturization of imaging elements is also advancing recently. There isdemand for miniaturization of imaging devices as a whole and imaginglenses to be mounted therein. Further, there is increasing demand for ashortening of the total length of imaging lenses to be mounted indevices which are becoming progressively thinner, such as cellulartelephones, smart phones, and tablet type terminals. In addition,imaging lenses having wider angles of view are in demand for imagingapparatuses such as cellular telephones, smart phones, and tablet typeterminals, which are often employed to enlarge photographed images witha digital zoom function, in order to realize a wider photography range.The imaging lens having the six lens configuration disclosed in KoreanPatent Publication No. 2010-0040357 has an angle of view ofapproximately 42 degrees, and is also required to have a furthershortened total length in order to meet the above demand.

The present disclosure has been developed in view of the foregoingpoints. The present disclosure provides an imaging lens that can realizea shortening of the total length, a wide angle of view, and high imagingperformance which is compatible with a greater number of pixels. Thepresent disclosure also provides an imaging apparatus equipped with thelens, which is capable of obtaining high resolution photographed images.

An imaging lens of the present disclosure consists of six lenses,including, in order from the object side to the image side:

a first lens having a positive refractive power and a convex surfacetoward the object side;

a second lens having a negative refractive power;

a third lens, which is a meniscus lens having a positive refractivepower and a convex surface toward the object side;

a fourth lens having a positive refractive power;

a fifth lens having a negative refractive power and a concave surfacetoward the object side; and

a sixth lens having a negative refractive power, of which the imagetoward the image side is of an aspherical shape which is concave in thevicinity of the optical axis and convex at the peripheral portionthereof;

the conditional formulae below being satisfied:

1.54<f/f4<3  (1)

0.5<f/f1<1  (2)

wherein f is the focal length of the entire lens system, f1 is the focallength of the first lens, and f4 is the focal length of the fourth lens.

It is preferable for one of Conditional Formulae (1-1) through (4-2)below to be satisfied in the imaging lens of the present disclosure.Note that as a preferred aspect, any one or arbitrary combinations ofConditional Formulae (1-1) through (4-2) may be satisfied.

1.55<f/f4<2.5  (1-1)

1.55<f/f4<2.2  (1-2)

0.5<f/f1<1  (2)

0.6<f/f1<0.95  (2-1)

0.65<f/f1<0.9  (2-2)

−0.3<f/f23456<0.4  (3)

−0.2<f/f23456<0.3  (3-1)

−0.15<f/f23456<0.25  (3-2)

−0.7<(R1f−R1r)/(R1f+R1r)<0  (4)

−0.65<(R1f−R1r)/(R1f+R1r)<−0.1  (4-1)

−0.62<(R1f−R1r)/(R1f+R1r)<−0.2  (4-2)

wherein f is the focal length of the entire lens system, f1 is the focallength of the first lens, f4 is the focal length of the fourth lens,f23456 is the combined focal length of the second lens through the sixthlens, R1 f is the paraxial radius of curvature of the surface of thefirst lens toward the object side, and R1 r is the paraxial radius ofcurvature of the surface of the first lens toward the image side.

In the imaging lens of the present disclosure, it is preferable for thesecond lens to be a meniscus lens having a convex surface toward theobject side.

In the imaging lens of the present disclosure, it is preferable for thefourth lens to be a meniscus lens having a concave surface toward theobject side.

In the imaging lens of the present disclosure, it is preferable for anaperture stop to be positioned at the object side of the surface of thesecond lens toward the object side.

Note that in the imaging lenses of the present disclosure, theexpression “consists of six lenses” means that the imaging lens of thepresent disclosure may also include lenses that practically have nopower, optical elements other than lenses such as a stop and a coverglass, and mechanical components such as lens flanges, a lens barrel, animaging element, a camera shake correcting mechanism, etc., in additionto the six lenses.

Note that in the imaging lenses of the present disclosure and thepreferred configurations thereof, the shapes of the surfaces of thelenses and the signs of the refractive indices thereof are considered inthe paraxial region in the case that the lenses include asphericalsurfaces. In addition, the signs of the paraxial radii of curvature arepositive in cases that the surface shape is convex toward the objectside, and negative in cases that the surface shape is convex toward theimage side.

An imaging apparatus of the present disclosure is equipped with animaging lens of the present disclosure.

According to the imaging lenses of the present disclosure, theconfiguration of each lens element is optimized within a lensconfiguration having six lenses as a whole. Particularly, the shapes ofthe first lens, the third lens, the fifth lens, and the sixth lens arefavorably configured, and the refractive power of the fourth lens isfavorably set. In addition, the imaging lenses are configured such thata predetermined conditional formula is satisfied. Therefore, a lenssystem that can achieve a short total length and has high imagingperformance can be realized.

The imaging apparatus of the present disclosure is equipped with animaging lens of the present disclosure as described above. Therefore, itis possible to shorten the size of the apparatus in the direction of theoptical axis of the imaging lens, and the imaging apparatus of thepresent disclosure is capable of obtaining high resolution photographedimages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional diagram that illustrates a first example of theconfiguration of an imaging lens according to an embodiment of thepresent disclosure, and corresponds to a lens of Example 1.

FIG. 2 is a sectional diagram that illustrates a second example of theconfiguration of an imaging lens according to an embodiment of thepresent disclosure, and corresponds to a lens of Example 2.

FIG. 3 is a sectional diagram that illustrates a third example of theconfiguration of an imaging lens according to an embodiment of thepresent disclosure, and corresponds to a lens of Example 3.

FIG. 4 is a sectional diagram that illustrates a fourth example of theconfiguration of an imaging lens according to an embodiment of thepresent disclosure, and corresponds to a lens of Example 4.

FIG. 5 is a sectional diagram that illustrates a fifth example of theconfiguration of an imaging lens according to an embodiment of thepresent disclosure, and corresponds to a lens of Example 5.

FIG. 6 is a sectional diagram that illustrates a sixth example of theconfiguration of an imaging lens according to an embodiment of thepresent disclosure, and corresponds to a lens of Example 6,

FIG. 7 is a diagram that illustrates the paths of light rays that passthrough the imaging lens of FIG. 1.

FIG. 8 is a collection of diagrams that illustrate aberrations of theimaging lens of Example 1, wherein A illustrates spherical aberration, Billustrates astigmatism, C illustrates distortion, and D illustrateslateral chromatic aberration.

FIG. 9 is a collection of diagrams that illustrate aberrations of theimaging lens of Example 2, wherein A illustrates spherical aberration, Billustrates astigmatism, C illustrates distortion, and D illustrateslateral chromatic aberration.

FIG. 10 is a collection of diagrams that illustrate aberrations of theimaging lens of Example 3, wherein A illustrates spherical aberration, Billustrates astigmatism, C illustrates distortion, and D illustrateslateral chromatic aberration.

FIG. 11 is a collection of diagrams that illustrate aberrations of theimaging lens of Example 4, wherein A illustrates spherical aberration, Billustrates astigmatism, C illustrates distortion, and D illustrateslateral chromatic aberration.

FIG. 12 is a collection of diagrams that illustrate aberrations of theimaging lens of Example 5, A illustrates spherical aberration, Billustrates astigmatism, C illustrates distortion, and D illustrateslateral chromatic aberration.

FIG. 13 is a collection of diagrams that illustrate aberrations of theimaging lens of Example 6, wherein A illustrates spherical aberration, Billustrates astigmatism, C illustrates distortion, and D illustrateslateral chromatic aberration.

FIG. 14 is a diagram that illustrates a cellular telephone as an imagingapparatus equipped with the imaging lens of the present disclosure.

FIG. 15 is a diagram that illustrates a smart phone as an imagingapparatus equipped with the imaging lens of the present disclosure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the attached drawings.

FIG. 1 illustrates a first example of the configuration of an imaginglens according to an embodiment of the present disclosure. This examplecorresponds to the lens configuration of Numerical Example 1 (Table 1and Table 2), to be described later. Similarly, FIG. 2 through FIG. 6are sectional diagrams that illustrate second through seventh examplesof lens configurations that correspond to Numerical Examples 2 through 6(Table 3 through Table 12). In FIGS. 1 through 6, the symbol Rirepresents the radii of curvature of ith (i=1, 2, 3, . . . ) surfaces.The symbol Di represents the distances between an ith surface and an i+1st surface along an optical axis Z1. Note that the basic configurationsof the examples are the same, and therefore a description will be givenof the imaging lens of FIG. 1 as a base. In addition, FIG. 7 is adiagram that illustrates the paths of light rays that pass through theimaging lens L of FIG. 1. FIG. 7 illustrates the paths of axial lightbeams 2 and maximum angle of view light beams 3 from an object at adistance of infinity.

The imaging lens of the embodiment of the present disclosure isfavorably employed in various imaging devices that employ imagingelements such as a CCD and a CMOS. The imaging lens of the embodiment ofthe present disclosure is particularly favorable for use incomparatively miniature portable terminal devices, such as a digitalstill camera, a cellular telephone with a built in camera, a smartphone, a tablet type terminal, and a PDA.

FIG. 14 schematically illustrates a cellular telephone as an imagingapparatus 1 according to an embodiment of the present disclosure. Theimaging apparatus 1 of the embodiment of the present disclosure isequipped with an imaging lens L according to the embodiment of thepresent disclosure and an imaging element 100 (refer to FIG. 1) such asa CCD that outputs image signals corresponding to optical images formedby the imaging lens L. The imaging element 100 is provided at an imageformation plane (imaging surface R16) of the imaging lens L.

FIG. 15 schematically illustrates a smart phone as an imaging apparatus501 according to an embodiment of the present disclosure. The imagingapparatus 501 of the embodiment of the present disclosure is equippedwith a camera section 541 having the imaging lens L according to theembodiment of the present disclosure and an imaging element 100 (referto FIG. 1) such as a CCD that outputs image signals corresponding tooptical images formed by the imaging lens L.

As illustrated in FIG. 1, the imaging lens L is equipped with, in orderfrom the object side to the image side, a first lens L1, a second lensL2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lensL6, provided along the optical axis Z1.

Various optical members CG may be provided between the sixth lens L6 andthe imaging element 100, depending on the configuration of the camera towhich the lens is applied. A planar optical member such as a cover glassfor protecting the imaging surface and an infrared cutoff filter may beprovided, for example. In this case, a planar cover glass having acoating having a filtering effect such as an infrared cutoff filtercoating or an ND filter coating, or a material that exhibits similareffects, may be utilized as the optical member CG.

Alternatively, the optical member CG may be omitted, and a coating maybe administered on the sixth lens L6 to obtain the same effect as thatof the optical member CG In this case, the number of parts can bereduced, and the total length can be shortened.

It is preferable for the imaging lens L to be equipped with an aperturestop St positioned at the object side of the surface of the second lensL2 toward the object side. In the case that the aperture stop St ispositioned at the object side of the surface of the second lens L2toward the object side in this manner, increases in the incident anglesof light rays that pass through the optical system and enter the imageformation plane (imaging element) can be suppressed, particularly atperipheral portions of an imaging region, which is advantageous from theviewpoint of widening the angle of view. It is more preferable for theaperture stop St to be positioned at the image side of the surface ofthe first lens L1 toward the object side. By positioning the aperturestop St at the object side of the surface of the first lens L1 towardthe image side in this manner, increases in the incident angles of lightrays that pass through the optical system and enter the image formationplane (imaging element) can be more favorably suppressed, and higheroptical performance can be realized.

Note that the expression “positioned at the object side of the surfaceof the second lens L2 toward the object side” means that the position ofthe aperture stop in the direction of the optical axis is at the sameposition as the intersection of marginal axial rays of light and thesurface of the second lens L2 toward the object side, or more toward theobject side than this position. Note that the expression “positioned atthe image side of the surface of the first lens L1 toward the objectside” means that the position of the aperture stop in the direction ofthe optical axis is at the same position as the intersection of marginalaxial rays of light and the surface of the first lens L1 toward theimage side, or more toward the object side than this position.

In the present embodiment, the aperture stop St is positioned at theimage side of the apex of the surface of the first lens L1 toward theobject side. However, the present disclosure is not limited to thisconfiguration, and the aperture stop St may be positioned at the objectside of the apex of the surface of the first lens L1 toward the objectside. A case in which the aperture stop St is positioned at the objectside of the apex of the surface of the first lens L1 toward the objectside is somewhat disadvantageous from the viewpoint of securingperipheral light intensity compared to a case in which the aperture stopSt is positioned at the image side of the apex of the surface of thefirst lens L1 toward the object side. However, increases in the incidentangles of light rays that pass through the optical system and enter theimage formation plane (imaging element) can be further suppressed at theperipheral portions of the imaging region. Note that the aperture stopsSt illustrated in FIG. 1 through FIG. 7 do not necessarily represent thesizes or shapes thereof, but indicate the positions thereof on theoptical axis Z1.

In the imaging lens L, the first lens L1 has a positive refractive powerin the vicinity of the optical axis, and has a convex surface toward theobject side in the vicinity of the optical axis. This configurationenables a favorable shortening of the total length of the lens. Inaddition, by configuring the first lens L1 to have a convex surfacetoward the object side, the surface of the lens system most toward theobject side is convex. Therefore, rearward principal point of theimaging lens can be moved toward the object side, and the total lengthof the lens can be favorably shortened. It is preferable for the firstlens L1 to be a meniscus lens having a convex surface toward the objectside in the vicinity of the optical axis. This configuration is evenmore advantageous from the viewpoint of shortening the total length ofthe lens.

The second lens L2 has a negative refractive power in the vicinity ofthe optical axis. It is preferable for the second lens L2 to have aconcave surface toward the image side in the vicinity of the opticalaxis. This configuration is advantageous from the viewpoint ofshortening the total length of the lens. In addition, it is preferablefor the second lens L2 to be a meniscus lens in the vicinity of theoptical axis. This configuration is even more advantageous from theviewpoints of shortening the total length of the lens and widening theangle of view. In addition, in the case that the second lens L2 has aconvex surface toward the object side in the vicinity of the opticalaxis, the total length can be even more favorably shortened, anddifferences in spherical aberration depending on wavelength can besuppressed with respect to light rays of different wavelengths.

The third lens L3 has a positive refractive power in the vicinity of theoptical axis, and is a meniscus lens having a convex surface toward theobject side in the vicinity of the optical axis. Configuring the thirdlens L3 to be a meniscus lens having a convex surface toward the objectside in the vicinity of the optical axis is advantageous from theviewpoints of shortening the total length of the lens and widening theangle of view. In addition, by configuring the third lens L3 to be of ashape having a convex surface toward the object side in the vicinity ofthe optical axis, the convex surface of the third lens L3 toward theobject side will correspond with the concave surface of the second lensL2 in the case that the surface of the second lens L2 toward the imageside is concave. Therefore, the distance along the optical axis betweenthe second lens L2 and the third lens L3 can be shortened, and the totallength of the lens can be shortened further.

The fourth lens L4 has a positive refractive power in the vicinity ofthe optical axis. This configuration is advantageous from the viewpointof shortening the total length of the lens. It is preferable for thefourth lens L4 to be a meniscus lens in the vicinity of the opticalaxis. In this case, correction of astigmatism will be facilitated.Correction of astigmatism will be facilitated further in the case thatthe fourth lens L4 is a meniscus lens having a concave surface towardthe object side.

The fifth lens L5 has a negative refractive power in the vicinity of theoptical axis. This configuration is advantageous from the viewpoint ofshortening the total length of the lens. In addition, the fifth lens L5has a concave surface toward the object side in the vicinity of theoptical axis. By configuring the fifth lens L5 to have a concave surfacetoward the object side in the vicinity of the optical axis, correctionof astigmatism will be facilitated, and this configuration is alsoadvantageous from the viewpoint of widening the angle of view. Inaddition, it is preferable for the fifth lens L5 to be a meniscus lenshaving a concave surface toward the object side in the vicinity of theoptical axis. In this case, correction of astigmatism will befacilitated further.

The sixth lens L6 has a negative refractive power in the vicinity of theoptical axis. This configuration is advantageous from the viewpoint ofshortening the total length of the lens. In addition, sixth lens L6 hasa concave surface toward the image side in the vicinity of the opticalaxis. By configuring the sixth lens L6 of the imaging lens L to have aconcave surface toward the image side in the vicinity of the opticalaxis, a shortening of the total length of the lens can be favorablyrealized. In addition, it is preferable for the sixth lens L6 to be ameniscus lens having a concave surface toward the image side in thevicinity of the optical axis. This configuration is advantageous fromthe viewpoints of shortening the total length of the lens and correctingfield curvature.

Further the surface of the sixth lens L6 toward the image side is of anaspherical shape which is concave in the vicinity of the optical axisand convex at the peripheral portion thereof. That is, the surface ofthe sixth lens L6 toward the image side is an aspherical shape having aninflection point within the effective diameter thereof. That the surfaceof the sixth lens L6 toward the image side has an “inflection point”means that there is a point at which a curve formed by the cross sectionof the surface of the sixth lens L6 toward the image side within theeffective diameter that includes the optical axis Z1 changes from aconvex shape to a concave shape (or from a concave shape to a convexshape). In addition, the peripheral portion here refers to a portiontoward the exterior of 60% of the effective diameter in the radialdirection. By configuring the surface of the sixth lens L6 toward theimage side to be of an aspherical shape which is concave in the vicinityof the optical axis and convex at the peripheral portion thereof,increases in the incident angles of light rays that pass through theoptical system and enter the image formation plane (imaging element) canbe suppressed, particularly at peripheral portions of the imagingregion. As a result, a decrease in the light receiving efficiency at theperipheral portions of the imaging region can be suppressed, whilerealizing a shortening of the total length of the lens.

The imaging lens L is capable of favorably shortening the total lengthof the lens and widening the angle of view, by the configurations of thefirst lens L1 having a positive refractive power and a convex surfacetoward the object side, the second lens L2 having a negative refractivepower, the third lens L3, which is a meniscus lens having a positiverefractive power and a convex surface toward the object side, and thefourth lens L4 having a positive refractive power, provided in thisorder from the object side. Further, the rearward principal point of theentire lens system can be positioned toward the object side, and thetotal length of the lens can be favorably shortened, by providing thefifth lens L5 and the sixth lens L6 having negative refractive powersadjacent to the fourth lens L4 toward the image side thereof.

It is preferable for at least one of the surfaces of each of the firstlens L1 through the sixth lens L6 of the imaging lens L to be anaspherical surface, in order to improve performance.

In addition, it is preferable for the first lens L1 through the sixthlens L6 that constitute the imaging lens L to be single lenses, notcemented lenses. In this case, the number of lens surfaces will begreater than that for a case in which any of the first lens L1 throughthe sixth lens L6 is a cemented lens, and thereby an increase in thenumber of aspherical surfaces becomes possible. Therefore, the degree offreedom in the design of each lens will increase. As a result, ashortening of the total length can be favorably achieved.

In addition, in the case that the configurations of each of the firstlens L1 through the sixth lens L6 are set such that the full angle ofview is 60 degrees or greater as in the example illustrated in FIG. 7,the imaging lens L may be favorably applied to cellular telephoneterminals and the like, which are often used for close distancephotography.

Next, the operation and effects related to conditional formulae to besatisfied by the imaging lens L configured as described above will bedescribed.

First, the imaging lens L satisfies Conditional Formula (1) below.

1.54<f/f4<3  (1)

wherein f is the focal length of the entire lens system, and f4 is thefocal length of the fourth lens.

It is preferable for one or arbitrary combinations of the conditionalformulae below to be satisfied in the imaging lens L. It is preferablefor the conditional formulae to be satisfied to be selected according toitems required of the imaging lens L.

0.5<f/f1<1  (2)

−0.3<f/f23456<0.4  (3)

−0.7<(R1f−R1r)/(R1f+R1r)<0  (4)

wherein f is the focal length of the entire lens system, f1 is the focallength of the first lens, f23456 is the combined focal length of thesecond lens through the sixth lens, R1 f is the paraxial radius ofcurvature of the surface of the first lens toward the object side, andR1 r is the paraxial radius of curvature of the surface of the firstlens toward the image side.

Hereinafter, the operation and effects of the above conditional formulaewill be described.

Conditional Formula (1) defines a preferable range of numerical valuesfor the focal length f of the entire lens system with respect to thefocal length f4 of the fourth lens L4. By securing the refractive powerof the fourth lens L4 such that the value of f/f4 is not less than orequal to the lower limit defined in Conditional Formula (1), ashortening of the total length of the lens can be favorably realized. Bysuppressing the refractive power of the fourth lens L4 such that thevalue of f/f4 is not greater than or equal to the upper limit defined inConditional Formula (1), spherical aberration can be favorablycorrected.

By configuring the imaging lens such that Conditional Formula (1) issatisfied, spherical aberration can be favorably corrected, while thelength of the entire lens system can be favorably shortened. It is morepreferable for Conditional Formula (1-1) to be satisfied, and even morepreferable for Conditional Formula (1-2) to be satisfied, in order tocause these advantageous effects to become more prominent.

1.55<f/f4<2.5  (1-1)

1.55<f/f4<2.2  (1-2)

Conditional Formula (2) defines a preferable range of numerical valuesfor the ratio of the focal length f of the entire lens system withrespect to the focal length f1 of the first lens L1. By securing therefractive power of the first lens L1 such that the value of f/f1 is notless than or equal to the lower limit defined in Conditional Formula(2), a shortening of the total length of the lens can be favorablyrealized. By suppressing the refractive power of the first lens L1 suchthat the value of f/f1 is not greater than or equal to the upper limitdefined in Conditional Formula (2), spherical aberration and astigmatismat low angles of view can be favorably corrected.

By configuring the imaging lens such that Conditional Formula (2) issatisfied, spherical aberration and astigmatism at low angles of viewcan be favorably corrected, while the length of the entire lens systemcan be shortened. It is more preferable for Conditional Formula (2-1) tobe satisfied, and even more preferable for Conditional Formula (2-2) tobe satisfied, in order to cause these advantageous effects to becomemore prominent.

0.6<f/f1<0.95  (2-1)

0.65<f/f1<0.9  (2-2)

Conditional Formula (3) defines a preferable range of numerical valuesfor the ratio of the focal length f of the entire lens system withrespect to the combined focal length of the second lens L2 through thesixth lens L6. That is, Conditional Formula (3) defines a preferablerange of numerical values for the ratio of the refractive power of acombined optical system constituted by combining the lenses other thanthe first lens L1 with respect to the refractive power of the entirelens system. By setting the refractive power of the combined opticalsystem that excludes the first lens L1 such that the value of f/f23456is not less than or equal to the lower limit defined in ConditionalFormula (3), astigmatism can be favorably corrected, and thisconfiguration is also advantageous from the viewpoint of widening theangle of view. Setting the refractive power of the combined opticalsystem that excludes the first lens L1 such that the value of f/f23456is not greater than or equal to the upper limit defined in ConditionalFormula (3) is advantageous from the viewpoint of shortening the totallength of the lens.

By configuring the imaging lens such that Conditional Formula (3) issatisfied, astigmatism can be favorably corrected and a widening of theangle of view can be achieved, while the length of the entire lenssystem can be shortened. It is more preferable for Conditional Formula(3-1) to be satisfied, and even more preferable for Conditional Formula(3-2) to be satisfied, in order to cause these advantageous effects tobecome more prominent.

−0.2<f/f23456<0.3  (3-1)

−0.15<f/f23456<0.25  (3-2)

Conditional Formula (4) defines a preferable range of numerical valuesrelated to the paraxial radius of curvature R1 f of the surface of thefirst lens L1 toward the object side and the paraxial radius ofcurvature R1 r of the surface of the first lens L1 toward the imageside. By setting the paraxial radius of curvature of the surface of thefirst lens L1 toward the object side and the paraxial radius ofcurvature of the surface of the first lens L1 toward the image side suchthat the value of (R1 f−R1 r)/(R1 f+R1 r) is not less than or equal tothe lower limit defined in Conditional Formula (4), the radius ofcurvature of the surface of the first lens L1 toward the image side canbe prevented from becoming excessively small with respect to the radiusof curvature of the surface of the first lens L1 toward the object side.This configuration is advantageous from the viewpoint of shortening thetotal length of the lens. By setting the paraxial radius of curvature ofthe surface of the first lens L1 toward the object side and the paraxialradius of curvature of the surface of the first lens L1 toward the imageside such that the value of (R1 f−R1 r)/(R1 f+R1 r) is not greater thanor equal to the upper limit defined in Conditional Formula (4), theradius of curvature of the surface of the first lens L1 toward the imageside can be prevented from becoming excessively great with respect tothe radius of curvature of the surface of the first lens L1 toward theobject side. As a result, spherical aberration and astigmatism can befavorably corrected.

By configuring the imaging lens such that Conditional Formula (4) issatisfied, spherical aberration and astigmatism can be favorablycorrected, while the total length of the lens can be favorablyshortened. It is more preferable for Conditional Formula (4-1) to besatisfied, and even more preferable for Conditional Formula (4-2) to besatisfied, in order to cause these advantageous effects to become moreprominent.

−0.65<(R1f−R1r)/(R1f+R1r)<−0.1  (4-1)

−0.62<(R1f−R1r)/(R1f+R1r)<−0.2  (4-2)

Next, specific examples of numerical values of the imaging lens of thepresent disclosure will be described. A plurality of examples ofnumerical values will be summarized and explained below.

Table 1 and Table 2 below show specific lens data corresponding to theconfiguration of the imaging lens illustrated in FIG. 1. Table 1 showsbasic lens data of the imaging lens, and Table 2 shows data related toaspherical surfaces. In the lens data of Table 1, ith surface numbersthat sequentially increase from the object side to the image side, withthe surface of the aperture stop St designated as first and the lenssurface at the most object side (the surface of the first lens L1 towardthe object side) designated as second, are shown in the column Si forthe imaging lens of Example 1. The radii of curvature (mm) of ithsurfaces from the object side corresponding to the symbols Riillustrated in FIG. 1 are shown in the column Ri. Similarly, thedistances (mm) between an ith surface Si and an i+1st surface Si+1 fromthe object side along the optical axis Z are shown in the column Di. Therefractive indices of jth optical elements from the object side withrespect to the d line (wavelength: 587.6 nm) are shown in the columnNdj. The Abbe's numbers of the jth optical elements with respect to thed line are shown in the column vdj. Note that the signs of the radii ofcurvature are positive in cases that the surface shape is convex towardthe object side, and negative in cases that the surface shape is convextoward the image side.

Note that the focal length f of the entire lens system (mm), the backfocus Bf (mm), the F number Fno., the full angle of view 2ω(°), and thetotal length TL of the lens system are shown as various items of dataabove the frame of Table 1. Note that the back focus Bf is representedas an air converted value. The total length TL of the lens system is thedistance along the optical axis from the surface of the first lens L1toward the object side to the imaging surface, in which the portioncorresponding to the back focus Bf is an air converted value.

In the imaging lens of Example 1, both of the surfaces of the first lensL1 through the sixth lens L6 are all aspherical in shape. In the basiclens data of Table 1, numerical values of radii of curvature in thevicinity of the optical axis (paraxial radii of curvature) are shown asthe radii of curvature of the aspherical surfaces.

Table 2 shows aspherical surface data of the imaging lens of Example 1.In the numerical values shown as the aspherical surface data, the symbol“E” indicates that the numerical value following thereafter is a “powerindex” having 10 as a base, and that the numerical value represented bythe index function having 10 as a base is to be multiplied by thenumerical value in front of “E”. For example, “1.0E−02” indicates thatthe numerical value is “1.0·10⁻²”.

The values of coefficients An and K represented by the asphericalsurface shape formula (A) below are shown as the aspherical surfacedata. In greater detail, Z is the length (mm) of a normal line thatextends from a point on the aspherical surface having a height h to aplane perpendicular to the optical axis that contacts the apex of theaspherical surface.

Z=C·h ²/{1+(1−K·C ² ·h ²)^(1/2) }+ΣAn·h ^(n)  (A)

wherein Z is the depth of the aspherical surface (mm), h is the distancefrom the optical axis to the surface of the lens (height) (mm), C is theparaxial curvature=1/R (R is the paraxial radius of curvature), An is annth ordinal aspherical surface coefficient (n is an integer 3 orgreater), and K is an aspherical surface coefficient.

Specific lens data corresponding to the configuration of the imaginglens illustrated in FIG. 2 are shown in Table 3 and Table 4 as Example 2in the same manner as that for the imaging lens of Example 1. Similarly,specific lens data corresponding to the configurations of the imaginglenses illustrated in FIG. 3 through FIG. 6 are shown in Table 5 throughTable 12 as Example 3 through Example 6. In the imaging lenses ofExample 1 through Example 6, both of the surfaces of the first lens L1through the sixth lens L6 are all aspherical surfaces.

A through D of FIG. 8 are a collection of diagrams that illustrateaberrations of the imaging lens of Example 1, wherein the diagramsillustrate the spherical aberration, the astigmatism, the distortion,and the lateral chromatic aberration (chromatic aberration ofmagnification) of the imaging lens of Example 1, respectively. Each ofthe diagrams that illustrate the spherical aberration, the astigmatism(field curvature), and the distortion illustrate aberrations using the dline (wavelength: 587.6 nm) as a reference wavelength. The diagrams thatillustrate spherical aberration and lateral chromatic aberration alsoshow aberrations related to the F line (wavelength: 486.1 nm), the Cline (wavelength: 656.3 nm) and the g line (wavelength: 435.83 nm). Inthe diagram that illustrates astigmatism, aberration in the sagittaldirection (S) is indicated by a solid line, while aberration in thetangential direction (T) is indicated by a broken line. In addition,“Fno.” denotes F numbers, and “ω” denotes a half value of the maximumangle of view in a state focused on an object at infinity.

Similarly, the aberrations of the imaging lens of Example 2 throughExample 6 are illustrated in A through D of FIG. 9 through A through Dof FIG. 13. The diagrams that illustrate aberrations of A through D ofFIG. 8 through A through D of FIG. 13 are all for cases in which theobject distance is infinity.

Table 13 shows values corresponding to Conditional Formulae (1) through(4), respectively summarized for each of Examples 1 through 6.

As can be understood from each set of numerical value data and from thediagrams that illustrate aberrations, the imaging lenses of Examples 1through 6 have wide angles of view of 80 degrees or greater and ratiosTL/f of the total length TL of the lens and the focal length f of theentire lens system within a range from 1.27 to 1.31. That is, theimaging lenses of Examples 1 through 6 realize a shortening of the totallength of the lens while favorably correcting various aberrations torealize high imaging performance.

Note that the imaging lens of the present disclosure is not limited tothe embodiments and Examples described above, and various modificationsare possible. For example, the values of the radii of curvature, thedistances among surfaces, the refractive indices, the Abbe's numbers,the aspherical surface coefficients, etc., are not limited to thenumerical values indicated in connection with the Examples of numericalvalues, and may be other values.

In addition, the Examples are described under the presumption that theyare to be utilized with fixed focus. However, it is also possible forconfigurations capable of adjusting focus to be adopted. It is possibleto adopt a configuration, in which the entirety of the lens system isfed out or a portion of the lenses is moved along the optical axis toenable automatic focus, for example.

TABLE 1 Example 1 f = 3.054, Bf = 0.995, Fno. = 2.41, 2ω = 81.8, TL =3.881 Si Ri Di Ndj νdj 1 (aperture stop) ∞ −0.109 *2 1.48851 0.4811.54492 55.89 *3 3.39432 0.189 *4 2.39108 0.262 1.63351 23.63 *5 1.677790.178 *6 5.64713 0.395 1.54492 55.89 *7 8.54563 0.169 *8 −14.70415 0.4001.54492 55.89 *9 −0.83298 0.100 *10 −2.22716 0.325 1.63351 23.63 *11−2.42944 0.112 *12 −32.65383 0.275 1.54492 55.89 *13 0.92208 0.400 14 ∞0.145 1.51633 64.14 15 ∞ 0.499 16 (imaging surface) ∞ *asphericalsurface

TABLE 2 Example 1 Surface Number 2 3 4 5 KA −6.2346485E−01−2.6172858E+00 6.8114850E+00 −2.7665192E+01 A3 −1.2307959E−02−1.0788950E−02 4.2859127E−02  6.6559934E−02 A4  9.3315008E−02−2.2417532E−01 −8.8181817E−01  −8.3760630E−02 A5 −1.4942742E−01 4.6279801E−01 1.6328721E+00  2.3719014E+00 A6  3.7131897E−01−1.2045159E+00 −3.8535568E+00  −1.0628656E+01 A7 −4.8596469E−01 9.7831456E−01 4.0760826E+00  1.9908455E+01 A8  3.2008593E−01 3.3120997E−01 −2.6512212E+00  −2.0436752E+01 A9 −1.9990218E−01−8.8537235E−01 1.6578776E+00  1.1635578E+01 A10  8.4168591E−02 3.1378939E−01 −4.1656627E−01  −2.8502725E+00 Surface Number 6 7 8 9 KA 3.9389929E+00 3.3248187E+01 −8.6027486E+00 −2.6910056E+00 A3−3.4157587E−02 −7.4744334E−02   1.8268020E−02  1.5052835E−01 A4 2.7037317E−01 4.2071241E−01 −1.2878481E−01 −4.2518864E−02 A5−1.7483469E+00 −3.0741293E+00   3.8218464E−01 −5.5875708E−01 A6 3.7590628E+00 7.4344630E+00 −6.4630278E−01  2.0624960E+00 A7−1.0881619E+00 −1.0532994E+01   4.7290273E−01 −3.4304983E+00 A8−5.6019946E+00 9.1600320E+00 −1.2250340E−01  3.4178769E+00 A9 6.9320804E+00 −4.5468708E+00  −1.3122944E−01 −1.8533026E+00 A10−2.5052533E+00 1.0192941E+00  7.8925890E−02  4.0172121E−01 SurfaceNumber 10 11 12 13 KA −5.5998956E+00 −1.4125479E+01  9.0340852E+00−4.9846651E+00 A3  2.5756464E−01  1.5894913E−01 −6.7808646E−02−1.3179047E−01 A4  7.0186630E−02 −7.1988189E−02 −2.5437722E−01−8.1475897E−02 A5 −3.8390564E−01 −1.1788154E−01  3.3050373E−01 2.5315519E−01 A6 −1.9775822E−03  6.3492697E−02 −7.9359956E−02−2.1982150E−01 A7  1.4513416E−01  2.7371630E−03 −5.6320755E−02 6.2033406E−02 A8 −4.8811676E−03  4.5987453E−03  3.6818926E−02 2.4349267E−02 A9  1.5207812E−02 −3.0755726E−03 −6.3771971E−03−2.0390224E−02 A10 −1.8986309E−02 −1.6257539E−04  4.9105600E−05 3.7795065E−03

TABLE 3 Example 2 f = 3.034, Bf = 0.973, Fno. = 2.16, 2ω = 82.0, TL =3.879 Si Ri Di Ndj νdj 1 (aperture stop) ∞ −0.129 *2 1.51385 0.4891.54492 55.89 *3 4.28784 0.201 *4 3.04013 0.263 1.63351 23.63 *5 1.852410.176 *6 7.31246 0.401 1.54492 55.89 *7 22.23331 0.165 *8 −10.983510.400 1.54492 55.89 *9 −0.74798 0.100 *10 −1.43253 0.325 1.63351 23.63*11 −2.01251 0.111 *12 6.61021 0.275 1.54492 55.89 *13 0.79041 0.400 14∞ 0.145 1.51633 64.14 15 ∞ 0.477 16 (imaging surface) ∞ *asphericalsurface

TABLE 4 Example 2 Surface Number 2 3 4 5 KA −6.3768363E−01−3.6515188E+00 6.9084607E+00 −2.8897945E+01 A3 −3.6678849E−02−3.9909150E−03 3.5653426E−02  2.8717163E−02 A4  3.0835437E−01−2.2288258E−01 −8.2769129E−01  −2.9280863E−02 A5 −9.4749695E−01 4.2646045E−01 1.5121944E+00  1.6049743E+00 A6  1.8218543E+00−1.3480768E+00 −3.5074036E+00  −7.2952907E+00 A7 −2.1746590E+00 1.5813259E+00 3.8863977E+00  1.3018856E+01 A8  2.3521836E+00−1.9517361E−01 −2.9150404E+00  −1.2457391E+01 A9 −2.5523740E+00−1.4670050E+00 1.5821644E+00  6.5281496E+00 A10  1.2506477E+00 9.5962275E−01 2.9378747E−03 −1.4321174E+00 Surface Number 6 7 8 9 KA−2.7320533E+01 −8.3349660E+00 2.7024535E+01 −2.6322193E+00 A3−5.7459708E−02 −1.1289481E−01 8.6398406E−03  1.3385304E−01 A4 3.8904410E−01  6.1174362E−01 −1.5016525E−01  −3.1325016E−02 A5−1.8537498E+00 −3.4422668E+00 4.3408801E−01 −4.5627655E−01 A6 3.5499103E+00  8.3994020E+00 −4.3828327E−01   1.8423968E+00 A7−7.1577856E−01 −1.2365894E+01 1.6107714E−01 −3.0898692E+00 A8−5.4450841E+00  1.1084286E+01 −6.3686023E−02   2.9980463E+00 A9 6.3294833E+00 −5.6078553E+00 −4.1192953E−02  −1.5781508E+00 A10−2.1927643E+00  1.2783382E+00 3.9274039E−02  3.3405388E−01 SurfaceNumber 10 11 12 13 KA −6.5075494E+00  −1.2123974E+01 −1.3379446E+01−4.2720944E+00 A3 2.7507054E−01  1.0817988E−01 −2.1874127E−01−1.7967109E−01 A4 9.4206971E−02 −5.8975439E−02 −2.4604774E−01−1.9410309E−02 A5 −3.8630138E−01  −3.3562334E−03  3.8676516E−01 1.6597318E−01 A6 3.7037260E−04  3.9388944E−02 −8.3764369E−02−1.3679023E−01 A7 1.3897427E−01 −7.4882781E−02 −6.5929100E−02 3.1227258E−02 A8 −1.2695310E−02   3.2943744E−02  3.7459973E−02 1.5417515E−02 A9 1.3631137E−02  5.7401815E−03 −5.7677694E−03−1.0178048E−02 A10 −1.5111878E−02  −3.8255889E−03  2.2141173E−05 1.6498232E−03

TABLE 5 Example 3 f = 3.141, Bf = 0.977, Fno. = 2.17, 2ω = 80.0, TL =3.997 Si Ri Di Ndj νdj 1 (aperture stop) ∞ −0.129 *2 1.48833 0.4871.54492 55.89 *3 4.94686 0.230 *4 9.48752 0.262 1.63351 23.63 *5 2.222650.100 *6 2.73360 0.394 1.54492 55.89 *7 10.32230 0.242 *8 −5.56426 0.4121.54492 55.89 *9 −0.93148 0.100 *10 −2.56865 0.416 1.63351 23.63 *11−2.77281 0.100 *12 3.50256 0.277 1.54492 55.89 *13 0.76788 0.400 14 ∞0.145 1.51633 64.14 15 ∞ 0.482 16 (imaging surface) ∞ *asphericalsurface

TABLE 6 Example 3 Surface Number 2 3 4 5 KA −6.8257158E−01 5.9306869E+003.1860734E+00 −4.3464563E+01 A3 −3.2195554E−02 2.3646292E−022.7303158E−02  4.0796052E−02 A4  2.3384061E−01 −3.9104220E−01 −7.0830188E−01  −3.5465782E−01 A5 −5.4227796E−01 1.1377927E+001.4777689E+00  2.2656166E+00 A6  1.3543725E+00 −2.3349203E+00 −4.2624399E+00  −8.2905427E+00 A7 −3.0713466E+00 1.4698015E+007.0274707E+00  1.5422080E+01 A8  4.5793308E+00 1.0524741E+00−6.0825041E+00  −1.6200867E+01 A9 −3.3716337E+00 −2.0412804E+00 5.8602734E−01  8.8596831E+00 A10  6.9025474E−01 5.6396366E−011.7628680E+00 −1.8202624E+00 Surface Number 6 7 8 9 KA −1.6381588E+01−2.5488489E+01 −3.7260327E+01 −2.5839109E+00 A3 −7.8345386E−02−1.7731060E−01  2.2423059E−02 −1.4137470E−01 A4  3.2907950E−01 1.2865579E+00 −4.1302562E−01  1.6266491E−01 A5 −1.0921537E+00−7.0576993E+00  6.9698079E−01 −5.4998574E−01 A6  1.8087664E+00 2.1283610E+01 −2.2257419E−01  2.0770710E+00 A7 −3.5178441E−01−3.8378604E+01 −8.2435076E−02 −3.4241627E+00 A8 −2.4376710E+00 4.0864589E+01 −1.1584125E−01  3.5039619E+00 A9  2.6430564E+00−2.3807256E+01  1.6163226E−02 −2.0282701E+00 A10 −8.7318318E−01 5.8592451E+00  3.7500877E−02  4.7225907E−01 Surface Number 10 11 12 13KA −5.9830680E+00 −5.0000009E+01 −1.1486844E+01 −4.0612259E+00 A3−1.1335939E−01 −1.1519417E−01 −3.1337462E−01 −1.6337009E−01 A4 2.8060636E−01  4.1546693E−02 −2.4526984E−01 −8.5663178E−02 A5 2.9339088E−02  1.6553685E−02  4.2310236E−01  2.2641286E−01 A6−2.6905658E−01 −1.5400149E−02 −8.3722667E−02 −1.3489630E−01 A7−5.5886652E−02 −7.5137309E−03 −7.2547268E−02  1.2709219E−02 A8 1.2845378E−01  1.0760256E−02  3.7571279E−02  1.8553809E−02 A9 5.8728703E−02 −7.8008349E−04 −5.2873743E−03 −8.3894149E−03 A10−4.8419546E−02 −7.3709948E−04  8.7599241E−07  1.1958322E−03

TABLE 7 Example 4 f = 3.105, Bf = 0.961, Fno. = 2.40, 2ω = 80.6, TL =3.942 Si Ri Di Ndj νdj 1 (aperture stop) ∞ −0.129 *2 1.48099 0.4811.54492 55.89 *3 4.94421 0.230 *4 9.29797 0.262 1.63351 23.63 *5 2.194970.100 *6 2.66541 0.394 1.54492 55.89 *7 9.54136 0.244 *8 −5.96433 0.4001.54492 55.89 *9 −0.93455 0.100 *10 −2.59033 0.386 1.63351 23.63 *11−2.75829 0.109 *12 3.57397 0.275 1.54492 55.89 *13 0.76071 0.400 14 ∞0.145 1.51633 64.14 15 ∞ 0.466 16 (imaging surface) ∞ *asphericalsurface

TABLE 8 Example 4 Surface Number 2 3 4 5 KA −6.8267210E−01 5.9323098E+002.4946575E+00 −4.3070224E+01 A3 −3.0420014E−02 2.5420361E−022.8762921E−02  4.6235341E−02 A4  2.2757069E−01 −3.9399579E−01 −7.1419203E−01  −3.6060442E−01 A5 −5.3704539E−01 1.1397057E+001.4823769E+00  2.2994838E+00 A6  1.3741545E+00 −2.3521044E+00 −4.2666602E+00  −8.4585734E+00 A7 −3.1072808E+00 1.5059811E+007.0222458E+00  1.5817045E+01 A8  4.5903344E+00 1.0583415E+00−6.0809649E+00  −1.6687192E+01 A9 −3.3798052E+00 −2.0930058E+00 6.1000250E−01  9.1450990E+00 A10  7.0092364E−01 5.7676159E−011.7517826E+00 −1.8754609E+00 Surface Number 6 7 8 9 KA −1.6395924E+01−2.8156019E+01 −3.7630084E+01 −2.5857888E+00 A3 −7.8594957E−02−1.8181767E−01  2.1928674E−02 −1.3677978E−01 A4  3.3618018E−01 1.3011575E+00 −4.2278662E−01  1.6262346E−01 A5 −1.0874646E+00−7.1381386E+00  7.0833815E−01 −5.4230016E−01 A6  1.8062409E+00 2.1548138E+01 −2.1403138E−01  2.0620909E+00 A7 −3.5503104E−01−3.8898595E+01 −8.5207306E−02 −3.3918067E+00 A8 −2.4394766E+00 4.1490311E+01 −1.2601141E−01  3.4541198E+00 A9  2.6508981E+00−2.4201929E+01  1.7612538E−02 −1.9935105E+00 A10 −8.7790978E−01 5.9566435E+00  3.9483575E−02  4.6367046E−01 Surface Number 10 11 12 13KA −5.9858733E+00 −5.0000009E+01 −1.1787918E+01 −4.0539689E+00 A3−1.0363928E−01 −1.0697421E−01 −3.2223544E−01 −1.7516243E−01 A4 2.9090961E−01  4.5141069E−02 −2.5615398E−01 −8.7228759E−02 A5 2.6484055E−02  1.1969313E−02  4.4277431E−01  2.4665066E−01 A6−2.8948681E−01 −1.8399287E−02 −8.5950022E−02 −1.5058826E−01 A7−5.5901445E−02 −6.5145623E−03 −7.7588245E−02  1.3916903E−02 A8 1.3922337E−01  1.1524681E−02  3.9524540E−02  2.1549325E−02 A9 5.8223045E−02 −8.6265817E−04 −5.4481564E−03 −9.6268578E−03 A10−4.9757008E−02 −7.9851941E−04 −1.2011366E−05  1.3515955E−03

TABLE 9 Example 5 f = 3.002, Bf = 0.942, Fno. = 2.20, 2ω = 80.6, TL =3.944 Si Ri Di Ndj νdj 1 (aperture stop) ∞ −0.129 *2 1.52994 0.4811.54492 55.89 *3 5.55305 0.254 *4 11.00085 0.262 1.63351 23.63 *52.36924 0.100 *6 2.85627 0.416 1.54492 55.89 *7 5.41383 0.199 *8−19.04865 0.450 1.54492 55.89 *9 −0.90518 0.100 *10 −2.71159 0.3651.63351 23.63 *11 −2.96668 0.100 *12 4.52761 0.275 1.54492 55.89 *130.78739 0.400 14 ∞ 0.145 1.51633 64.14 15 ∞ 0.447 16 (imaging surface) ∞*aspherical surface

TABLE 10 Example 5 Surface Number 2 3 4 5 KA −6.9763770E−011.7371847E+00 −2.5885072E+01  −4.1793719E+01 A3 −2.3148382E−021.1823386E−02 3.0025616E−02  5.5452932E−02 A4  1.5858869E−01−2.6161130E−01  −6.7918992E−01  −4.6284434E−01 A5 −3.8696791E−017.5866050E−01 1.4111395E+00  2.6182431E+00 A6  1.3455817E+00−2.1156964E+00  −4.2811265E+00  −9.2118443E+00 A7 −3.5785890E+002.2430552E+00 7.1638941E+00  1.7347343E+01 A8  5.2022080E+006.1693864E−02 −6.1295724E+00  −1.8760568E+01 A9 −3.4686147E+00−2.4284013E+00  3.7331631E−01  1.0655077E+01 A10  5.4746539E−011.3633281E+00 2.0861388E+00 −2.3045209E+00 Surface Number 6 7 8 9 KA−1.8546396E+01 −2.3267730E+01  2.8694409E+01 −2.7422177E+00 A3−6.9656440E−02 −1.4702377E−01  1.8335851E−02 −1.1432590E−01 A4 3.6376386E−01  9.2779496E−01 −4.5152552E−01  1.5798883E−01 A5−1.1722732E+00 −5.5255924E+00  6.8486800E−01 −7.6592736E−01 A6 1.9404018E+00  1.6902639E+01 −1.5605500E−01  2.3357449E+00 A7−3.6074642E−01 −2.9666269E+01 −5.1751592E−02 −3.6708200E+00 A8−2.6924542E+00  3.0212412E+01 −1.3195191E−01  3.9282227E+00 A9 2.9985438E+00 −1.6658101E+01 −1.9748691E−03 −2.3750912E+00 A10−1.0369343E+00  3.8209797E+00  3.5305152E−02  5.6520515E−01 SurfaceNumber 10 11 12 13 KA −5.2977099E+00 −4.6270026E+01 −1.1812850E+01−4.0797604E+00 A3 −2.5161724E−02 −2.5088384E−02 −2.2903117E−01−1.1894201E−01 A4  1.8073674E−01 −6.9346772E−03 −2.8815692E−01−1.6884388E−01 A5  2.0194750E−02 −4.2904036E−02  3.9758580E−01 3.2597927E−01 A6 −1.9650813E−01  2.4493077E−02 −6.3678630E−02−1.9365904E−01 A7 −7.9599266E−02  3.7301804E−03 −7.0842975E−02 1.6166184E−02 A8  1.0860707E−01  1.5859380E−03  3.4391570E−02 3.2514155E−02 A9  6.3978363E−02 −1.8882748E−03 −5.2209117E−03−1.4861819E−02 A10 −4.5123591E−02  1.0295558E−04  1.7549639E−04 2.0863763E−03

TABLE 11 Example 6 f = 3.038, Bf = 0.935, Fno. = 2.41, 2ω = 80.2, TL =3.877 Si Ri Di Ndj νdj 1 (aperture stop) ∞ −0.129 *2 1.48353 0.4811.54492 55.89 *3 5.89430 0.218 *4 10.23199 0.262 1.63351 23.63 *52.30136 0.100 *6 3.77092 0.394 1.54492 55.89 *7 37.33223 0.233 *8−11.32172 0.400 1.54492 55.89 *9 −0.97946 0.102 *10 −1.79154 0.3251.63351 23.63 *11 −1.91796 0.102 *12 3.25074 0.325 1.54492 55.89 *130.72407 0.400 14 ∞ 0.145 1.51633 64.14 15 ∞ 0.439 16 (imaging surface) ∞*aspherical surface

TABLE 12 Example 6 Surface Number 2 3 4 5 KA −6.2872607E−016.8677188E+00 −6.0446027E+00  −4.2792682E+01 A3 −4.6920696E−022.0709156E−02 1.9944048E−02  3.5906033E−02 A4  3.4599541E−01−3.7048700E−01  −5.7401837E−01  −1.2908121E−01 A5 −9.1824076E−011.0966423E+00 9.3805935E−01  1.4400769E+00 A6  1.7545129E+00−2.4567067E+00  −3.3073400E+00  −6.5085333E+00 A7 −2.7699361E+001.8382720E+00 6.2242496E+00  1.2558552E+01 A8  3.9521041E+009.1757492E−01 −5.8987134E+00  −1.2587419E+01 A9 −3.7119024E+00−2.4939143E+00  6.5567570E−01  6.0095317E+00 A10  1.2830653E+009.6365554E−01 1.8579091E+00 −8.9346778E−01 Surface Number 6 7 8 9 KA−1.4887156E+01 −4.9956685E+01 1.1629115E+01 −2.4290088E+00 A3−5.6912036E−02 −1.6599770E−01 2.2348265E−02 −7.0139107E−02 A4 4.3448989E−01  1.2480730E+00 −3.3317302E−01   7.2410019E−02 A5−1.6065038E+00 −6.6097493E+00 5.7688577E−01 −4.2539543E−01 A6 2.4658366E+00  1.8907704E+01 −3.5828067E−01   2.1604707E+00 A7−1.7982555E−01 −3.3178733E+01 1.8918943E−02 −4.0352538E+00 A8−3.6326699E+00  3.4758070E+01 −5.7216065E−02   4.1215138E+00 A9 3.8026544E+00 −1.9928580E+01 2.5814616E−03 −2.2123149E+00 A10−1.2559998E+00  4.8680547E+00 3.2722538E−02  4.7203674E−01 SurfaceNumber 10 11 12 13 KA −6.5385747E+00 −2.9177268E+01 −9.0748999E+00−4.2259820E+00 A3 −4.4118955E−02 −1.4653932E−01 −3.6252001E−01−1.7105206E−01 A4  2.4943152E−01  8.3142565E−02 −2.8734485E−01−5.3611639E−02 A5 −6.9190473E−02  5.8581337E−02  5.3460522E−01 1.8785365E−01 A6 −1.5949792E−01 −5.4434105E−02 −1.2690232E−01−1.2099698E−01 A7 −1.1289235E−02 −2.7815580E−02 −9.8506193E−02 1.7083394E−02 A8  5.7510037E−02  2.7664655E−02  5.9999193E−02 1.4549274E−02 A9  5.3241580E−02  5.7095066E−04 −9.2781506E−03−7.9100825E−03 A10 −3.4841967E−02 −2.3676939E−03 −1.7894119E−04 1.2884735E−03

TABLE 13 Values Related to Conditional Formulae Formula ConditionExample 1 Example 2 Example 3 Example 4 Example 5 Example 6 (1) f/f4 1.92.09 1.58 1.57 1.74 1.56 (2) f/f1 0.68 0.75 0.84 0.84 0.81 0.87 (3)f/f23456 0.2 0.1 −0.04 −0.04 0.04 −0.09 (4) (R1f − R1r) −0.39 −0.48−0.54 −0.54 −0.57 −0.6 (R1f + R1r)

What is claimed is:
 1. An imaging lens consisting of six lenses,including, in order from the object side to the image side: a first lenshaving a positive refractive power and a convex surface toward theobject side; a second lens having a negative refractive power; a thirdlens, which is a meniscus lens having a positive refractive power and aconvex surface toward the object side; a fourth lens having a positiverefractive power; a fifth lens having a negative refractive power and aconcave surface toward the object side; and a sixth lens having anegative refractive power, of which the image toward the image side isof an aspherical shape which is concave in the vicinity of the opticalaxis and convex at the peripheral portion thereof; the conditionalformulae below being satisfied:1.54<f/f4<3  (1)0.5<f/f1<1  (2) wherein f is the focal length of the entire lens system,f1 is the focal length of the first lens, and f4 is the focal length ofthe fourth lens.
 2. An imaging lens as defined in claim 1, in which theconditional formula below further is satisfied:−0.3<f/f23456<0.4  (3) wherein f23456 is the combined focal length ofthe second lens through the sixth lens.
 3. An imaging apparatus asdefined in claim 1, wherein: the second lens is a meniscus lens having aconvex surface toward the object side.
 4. An imaging lens as defined inclaim 1, wherein: the fourth lens is a meniscus lens having a concavesurface toward the object side.
 5. An imaging lens as defined in claim1, in which the conditional formula below is satisfied:−0.7<(R1f−R1r)/(R1f+R1r)<0  (4) wherein R1 f is the paraxial radius ofcurvature of the surface of the first lens toward the object side, andR1 r is the paraxial radius of curvature of the surface of the firstlens toward the image side.
 6. An imaging lens as defined in claim 1,further comprising: an aperture stop positioned at the object side ofthe surface of the second lens toward the object side.
 7. An imaginglens as defined in claim 1, in which the conditional formula below isfurther satisfied:1.55<f/f4<2.5  (1-1)
 8. An imaging lens as defined in claim 1, in whichthe conditional formula below is further satisfied:0.6<f/f1<0.95  (2-1) wherein f1 is the focal length of the first lens.9. An imaging lens as defined in claim 1, in which the conditionalformula below is further satisfied:−0.2<f/f23456<0.3  (3-1) wherein f23456 is the combined focal length ofthe second lens through the sixth lens.
 10. An imaging lens as definedin claim 1, in which the conditional formula below is further satisfied:−0.65<(R1f−R1r)/(R1f+R1r)<−0.1  (4-1) wherein R1 f is the paraxialradius of curvature of the surface of the first lens toward the objectside, and R1 r is the paraxial radius of curvature of the surface of thefirst lens toward the image side.
 11. An imaging lens as defined inclaim 1, in which the conditional formula below is further satisfied:1.55<f/f4<2.2  (1-2)
 12. An imaging lens as defined in claim 1, in whichthe conditional formula below is further satisfied:0.65<f/f1<0.9  (2-2) wherein f1 is the focal length of the first lens.13. An imaging lens as defined in claim 1, in which the conditionalformula below is further satisfied:−0.15<f/f23456<0.25  (3-2) wherein f23456 is the combined focal lengthof the second lens through the sixth lens.
 14. An imaging lens asdefined in claim 1, in which the conditional formula below is furthersatisfied:−0.62<(R1f−R1r)/(R1f+R1r)<−0.2  (4-2) wherein R1 f is the paraxialradius of curvature of the surface of the first lens toward the objectside, and R1 r is the paraxial radius of curvature of the surface of thefirst lens toward the image side.
 15. An imaging apparatus comprisingthe imaging lens defined in claim 1.